I. Field of the Invention
This invention relates generally to tissue biopsy apparatus, and more particularly to a biopsy instrument which may be used in combination with an endoscope for excising suspicious tissue samples from an interior wall of an internal organ and which incorporates a pair of bipolar electrodes at the distal end thereof for subsequently coagulating bleeding blood vessels following excision of the tissue sample.
II. Discussion of the Prior Art
The prior art device over which the present invention is deemed to be an improvement comprises an elongated tube having a reciprocally moveable control rod extending through the lumen thereof and affixed at its distal end are tiny clamshell-like tongs which can be made to open and close when a lever mechanism at the proximal end of the elongated tube is manipulated. The device is dimensioned to pass through an endoscope and, in use, the clamshell tongs, in their open disposition, are made to approach the vessel wall in a perpendicular direction at the location where the tissue sample is to be excised. Then, by manipulating the handle at the proximal end of the instrument, the tongs are made to close on the sample which is pinched and partially cut by the edges of the clamshell tongs. As skilled surgeons will appreciate, when a vessel wall is approached from the perpendicular direction, the chances for perforation of that vessel wall are considerably greater than when the approach is made at a 0.degree. angle relative to the wall.
The prior art instrument over which the present invention is deemed to be an improvement also provides for electrocautery. However, rather than being a bipolar device, it is monopolar, thereby requiring a large area body electrode positioned at a location on the skin surface quite remote from the site of the biopsy. The coagulating current is applied between the clamshell tip on the biopsy instrument and the body plate and, again, the risk of perforation is increased by virtue of the monopolar electrode configuration employed.
Another drawback of the above-described prior art biopsy instrument is that the tissue sample is held between the closed clamshell halves and during electrocautery, the sample may be destroyed by the high temperatures to which it is exposed. This may preclude a pathologist from accurately determining the nature of the cells contained in the excised sample.
The prior art instrument can only be used to remove a single sample from the vessel wall without having to first remove the instrument from the endoscope and then reinsert it to gather a second sample. This is due to the fact that after a first sample is excised and held in the jaws of the clamshell, it will be lost when the clamshell is reopened in an attempt to excise the second sample.
The linkage mechanism affixed to the distal end of the elongated tube for operating the clamshell halves is difficult to assemble which significantly increases the cost of the instrument. In fact, the cost is too high to allow the instrument to be considered as a practical single-use or disposable instrument.